GitLab

Enable the menu selection traversal with the tab key. In detail:
(1) If a menu item is under selection and its delete button is hidden,
after pressing the tab key, the delete button should show.
(2) If a menu item's delete button is under pseudo focus, after pressing
the tab key, the next selectable menu item after the current one is
selected.
(3) A menu item view is removed from the root menu asynchronously since
the item to be deleted may be accessed by MenuController.

Bug: 1134422, 1106847
Change-Id: I71abdbca619266f21543172d670960bea8580049
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2448674Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: David Black <dmblack@google.com>
Commit-Queue: Andrew Xu <andrewxu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#819992}